Electric Vehicle Kick-Up Bending Facilitating Portion
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Solution Overview
Problem
In electric vehicles, the existing floor structure design can lead to interference and damage to the battery unit during a lateral collision due to the breakability of cross-members, which increases the risk of severe damage.
Innovation Solution
A lower vehicle-body structure is designed with a kick-up having a closed cross-sectional part extending between side sills, where the side portions are bent downward and connected to the side sills, and a bending facilitating portion is formed outward of the bent portion to absorb collision loads, reducing the likelihood of interference with the battery unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cross-member under the kick-up has both end portions bent substantially downward to connect to side sills, then the structural strength is improved, but the cross-member becomes easily breakable in lateral collision, increasing the risk of interference with the battery unit
Solution Approach 1:
The kick-up cross-member is segmented into distinct functional zones: a bending facilitating portion with reduced thickness for controlled deformation, and thicker portions for structural strength. This segmentation allows different regions to serve different purposes during collision - the thin portion bends to absorb energy while thicker portions maintain structural integrity
Solution Approach 2:
The kick-up cross-member has non-uniform thickness distribution with a local thinning region at the bending facilitating portion. This local quality change creates a predetermined weak point that bends preferentially during lateral collision, preventing catastrophic failure of the entire structure and reducing interference with the battery unit
2Strength
If the bent portion of the kick-up is positioned toward the side sill to connect structurally, then the structural connection is improved, but the overhang beyond the bent portion increases, increasing the likelihood of interference with the battery unit in lateral collision
Solution Approach 1:
The bending facilitating portion is positioned outward of the bent portion to create a preliminary deformation zone that activates first during lateral collision. This preliminary action of bending at the facilitating portion reduces the overhang before the bent portion can interfere with the battery unit, preventing harmful effects in advance
Data Source
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AI summary
Provided is a lower vehicle-body structure of an electric vehicle including a bending facilitating portion that is located outward of a bent portion 41 of a kick-up 10 and bends as a breakage starter in a lateral collision, earlier than the bent portion 41, so as to reduce the amount of projection (so-called overhang) from the bending facilitating portion toward an outer side and reduce the likelihood of interference with a battery unit 21. Each of left and right side portions in a vehicle width direction of a kick-up 10 is bent substantially downward from a position inward of a rear side frame toward a side sill 2 and connected to the side sill 2. A bending facilitating portion b1 that facilitates bending under a lateral-collision load is formed outward of a bent portion 41 of the kick-up 10 and an outer side portion 21a of a battery unit 21, at a position inward of an inner end of the rear side frame or at substantially the same position as the inner end.